Various types of road vehicles are required, during positioning, to be levelled (i.e. disposed substantially horizontally) in at least one direction (typically in the lateral, “east-west” direction) and, in many cases, in two orthogonal, east-west and longitudinal (“north-south”) directions. Such road vehicles can include:
a) mobile cranes which must be levelled, normally using on-board hydraulic jacks, before being operated in a load lifting mode,
b) various product-transport trucks,
c) caravans (sometimes known as trailers), and
d) so-called motor homes.
The present disclosure will, for convenience, hereinafter largely pertain to the context of caravans but it is to be understood that the form and operation of the subject level indicator device and vehicle level adjusting system may be adapted to other relevant types of road vehicles, such as those set forth above.
In the case of caravans, levelling may be required for any one or more of a number of reasons, for example to facilitate efficient functioning of on-board refrigerator units (particularly those employing an absorption system), to provide for waste water drainage and for occupant comfort. Such levelling is almost always required in caravan parks, where uneven ground can be common, and even more so in off-site locations.
When positioning a caravan, for example, in a selected site, levelling currently is achieved by first assessing the degree and direction of localised east-west inclination of the site. This may be achieved by visual inspection of the site, using a trained eye, or, more usually, by placing a spirit level on or in the caravan. This is then followed by placing a ramp behind the wheel or each of the wheels in the case of a twin-axle caravan at the lower side of the caravan and by then reversing the caravan up the ramp(s) to the extent required to achieve a substantially horizontal disposition. Several attempts frequently are required to be made, even by experienced users of caravans, to achieve an acceptable degree of levelling (determined by reference to the spirit level) when employing this customary procedure, and it is recognised that this is one of the more stressful aspects of caravanning.
Following the east-west levelling, a measure is taken of the caravan inclination in the north-south direction, again customarily by use of a spirit level, and north-south levelling is effected by adjustment of the caravan jockey wheel, upwardly or downwardly as required.
References to the background art herein do not constitute an admission that the art forms a part of the common general knowledge of a person of ordinary skill in the art, in Australia or elsewhere.